As a conventional electric-vehicle drive controller, for example, Patent Literature 1 listed below discloses an apparatus that includes a filter device constituted by a filter reactor and a filter capacitor on an input side (a direct-current overhead-line side) of an inverter, thereby preventing a noise current generated when the inverter drives a motor from flowing out to the direct-current overhead-line side.
Meanwhile, when a noise current generated by an inverter is large or when a noise-current regulation value is small (that is, when the withstanding amount of the noise current is small), for example, there is a case of configuring a double-stage filter to further reliably prevent the noise current from flowing out, as described in Patent Literature 2 listed below.
The filter device disclosed in Patent Literature 2 is configured by using a filter reactor in which filters of a double-stage filter are magnetically coupled to each other for improving a noise-current suppression effect (a flowing-out prevention effect), as compared to the filter device described in Patent Literature 1. Further, in the filter device disclosed in Patent Literature 2, a third filter reactor is electrically connected to an intermediate tap drawn from a connection point of a first filter reactor constituting a first-stage filter and a second filter reactor constituting a second-stage filter. The third filter reactor is used for canceling a negative equivalent inductance generated by magnetic coupling of the first and second filter reactors. By providing the third filter reactor, it is made possible to obtain an originally intended double-stage filter. Accordingly, the noise-current attenuation characteristic in a high-frequency region that is degraded if the third filter reactor is not provided can be the noise-current attenuation characteristic originally intended for a double-stage filter. By using filter reactors that are magnetically coupled to each other, downsizing thereof can be achieved.